The Discharge Mechanism of Fast G-M Counters from the Deadtime Experiment

The deadtime of a self-quenching counter is an insensitive time, of the order of ${10}^{-4\mathrm{}}$ second, which occurs between the time when a counter registers a count and the time at which it has recovered sufficiently to register another count. A simple method of measurement of this time is shown. From a theory developed to explain this deadtime phenomenon it is possible to compute times associated with the deadtime. The check between theory and experiment is very good. The theory involves the formation of a positive ion space charge sheath about the wire of the counter, this sheath expanding to the cylinder. Not only is it possible to show the internal action of a counter by the deadtime experiment, but also it is possible to study the lengthwise spread of that discharge. It was found that the discharge spread throughout the length of the counter, but the spread could be stopped by a small glass bead on the wire. This discovery led to the construction of a directional Geiger counter.